Couplers are used for connecting two pipes. The couplers used are either cylindrical pipe sections into which one end of each pipe can be screwed or pushed and fastened in some manner from each side. However, it is also possible, during production, to provide one end of a pipe with an extension which serves as a coupler and into which the unextended end of an identical pipe can then be pushed. These two methods are also known in the case of plastic pipes. The advantages and the disadvantages of these types of couplers are also known.
To ensure a tight connection between the pipe and the sleeve, either the pipe or the coupler can be provided with sealing means. It is known that a groove can be provided close to the pipe end, in which groove a sealing means, such as, for example, an 0-ring or something similar, is housed. Since this reduces the wall thickness of the pipe, which is undesirable particularly in pipes which are laid in the ground and are governed by the pressing method, and therefore should be avoided, couplers which consist of a resilient inner part provided with lips and a covering of solid material applied on said inner part are also known. Couplers of this type are very complicated to produce and are therefore expensive.